16Hit1600
Advanced MathMediumConstant after expanding and combining two products

Advanced Math practice question

For all values of x, x(x + 3) − 3(x + 3) = x² − k, where k is a constant. What is the value of k?

Answer: 9

x² + 3x − 3x − 9 = x² − 9.

Common wrong answers

If you answered 3
3 copies the number in the factors.
If you answered 6
6 adds 3 and 3.
If you answered -9
−9 has the sign wrong for k.

More Advanced Math questions

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